<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../js/jquery.min.js"></script>
    <script>
        function f1(){
           console.log( $("li").parent()[0]);//jquery对象->DOM对象
        }
        function f2(){

            console.log( $("ul").children());
            console.log($("ul").children()[3]);//jquery对象->DOM对象
        }
    </script>
</head>
<body>
    <input type="button" value="获取父元素" onclick="f1()">
    <input type="button" value="获取子元素" onclick="f2()">
    <ul>
        <li>li01</li>
        <li>li02</li>
        <li>li03</li>
        <li>li04</li>
        <li>li05</li>
    </ul>
</body>
</html>